University of Sistan and Baluchestan, Iranian Society Of Mechanical Engineers Challenges in Nano and Micro Scale Science and Technology 2821-000X 14 2 2026 09 01 Catalytic Degradation of Tetracycline in Aqueous Solution Using Cu-Modified γ-MnO2 Nanostructures 45 56 10056 10.22111/cnmst.2026.55742.1308 EN Alireza Khorshidi Faculty Of Sciences, Namjoo Str. Rasht, Guilan Masoumeh Keramati Faculty of Chemistry, University of Guilan Journal Article 2026 06 10 Tetracycline antibiotics are among the most recalcitrant micropollutants detected in aquatic environments, posing significant threats to public health due to their low biodegradability, promotion of antibiotic resistance, and endocrine-disrupting potential. In this study, γ-MnO2 and Cu-modified γ-MnO2 (Cu-γ-MnO2) nanostructures were successfully synthesized and evaluated as heterogeneous catalysts for the oxidative degradation of tetracycline in aqueous solution in the presence of H2O2. The synthesized materials were thoroughly characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). XRD confirmed the pure γ-MnO2 phase for both materials, with Cu incorporation causing no new crystalline phases but inducing a slight reduction in crystallite size. FE-SEM revealed a unique hedgehog-like morphology with needle-shaped nanocrystals assembled into spherical superstructures (17–36 nm), which was preserved upon Cu modification. Under optimized conditions (pH 4, 55°C, 20 mg catalyst, 1 mL of 30% H2O2, 20 min), Cu-γ-MnO2 achieved 98% tetracycline degradation, significantly outperforming unmodified γ-MnO2 (70%). The reaction followed NLLS biphasic kinetics (k₁ = 1.343 min−1 (R2 = 0.979). The Cu-γ-MnO2 catalyst demonstrated exceptional recyclability, retaining >80% activity after seven consecutive cycles, underscoring its practical feasibility for wastewater remediation applications. https://chal.usb.ac.ir/article_10056_067e0586b30697c2d8b6ee2b4c62ed1e.pdf